merge_pr_50009

Fenced frames: disableUntrustedNetwork() for WebTransport.

This CL prevents WebTransport connections from being created in frames
with network access revoked, and closes existing WebTransport
connections if a frame loses network access.

Change-Id: Iacb3eff60c8bbd4a154d3f9390f37ad966eafcb0
Bug: 385155392
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6113689
Reviewed-by: Xiaochen Zhou [email protected]
Commit-Queue: Liam Brady [email protected]
Reviewed-by: Kenichi Ishibashi [email protected]
Reviewed-by: Shivani Sharma [email protected]
Cr-Commit-Position: refs/heads/main@{#1404463}